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View Full Version : HP 125 boots cp/m at last



harry
June 24th, 2012, 10:21 AM
Just a few pics of my HP125 finally back together, and booting cp/m again. This machine was complete when I aquired it, and although it was showing no signs of life,and the screen looked really bad with gel rot, I really liked the strange look of this machine and was determined to put it back into working order.
The psu was good, the first of the two z80's was good,and by reading the fault LED's on the m/board the second Z80 was proven to be not working? After replacing this, and cleaning all other socketed ic's, it was a welcome sight to see some boot messages on screen.
The HD/floppy drive unit was not showing any signs of life, but again the psu checked out ok, I removed and stripped the HD, only to find the solenoid brake rusted to the flywheel! it took some getting free, but with come WD40 and some luck, I managed to get things free, and the flywheel rim as clean as possible.the floppy drive was also stripped, cleaned,and lubricated,
The drive was now spinning ok, and after leaving it on for a short time, I then powered on the Hp125, I could then press the key to load o/s.
and to my supprise application manager came up on screen, I could then choose cp/m, and dir from the A prompt, and was amased at erything still on the HD. As the machine was now working , I decided to tackle the screen problem, The dreaded "screen rot" this is actually the breaking down of the gel used to fill the viod between the outer safety glass and the front face of the crt. Only way is to remove the crt, make a suitable stand to support it,I cut a rectangular hole in some chipboard, and placed it over a waste bin, then using a hot air gun, and some patience, slowy bring the whole face, upto what seems a ridiculous amount of heat, until you can see the gel releasing itself from the glass, once removed, it was just a case of cleaning the gel from all surfaces, then I bonded the clean outer glass back to the face of the crt with silocone sealer,finally, sealed over the edges with black tape,refitted the crt, and hopefully the pics show it was all worth it! ........Harry

smp
June 24th, 2012, 12:20 PM
Wow. Nice job!
Your machine looks really nice.
Congratulations.

smp

leeb
June 24th, 2012, 12:53 PM
That's nice work!!!

Could I getcha to detail my car? :p

j/k :D

Pepinno
June 24th, 2012, 01:08 PM
A beautiful machine indeed.

And a nice restoration job.

Have you been able to read/write floppies yet? What is the size of the HDD? How much RAM does it have, 64 KB?

harry
June 26th, 2012, 02:05 PM
Thanks guys for replies, yes the floppy drive does work ok,and I was suprised the inbuilt thermal printer is also still working fine, I do like the build quality of the HP machines, strange how there seems little to come up on the forum relating to HP equipment, I guess most of their gear was directed toward buisness use, and it seems HP was not so forth coming with schematics, and repair info, as other manufactures, Hp also seem to have given many parts their own code . when it probably is a standard type part they have used, again making it harder for third party repair? finally I must add that without the HP MUSEUM in Australia, I don't know where else one could have access to such a huge documented site to help others using, or restoring HP equipment,it has certainly developed into a brilliant site , so much info and downloads. great stuff. .....Harry